Ubuntu
devmapper package

(dm-0 caused) creating lvm2 snapshot of root lv breaks boot

Bug #144049 reported by Ilya Petrov
2
Affects Status Importance Assigned to Milestone
devmapper (Ubuntu)
Fix Released
Undecided
Unassigned
grub (Baltix)
Invalid
Undecided
Unassigned

Bug Description

i`m using gutsy tribe5 with root fs on lvm2 volume (/dev/mapper/sunset-root) .
when i`m creating snapshot of root device (/dev/mapper/sunset-root--19--09) lvm creats three (!) devices
with same UUID:

before creating:
/dev/mapper/sunset-root (block 254,0) aka /dev/dm-0

after:
/dev/mapper/sunset-root-real (block 254,0) aka /dev/dm-0 (oops!)
/dev/mapper/sunset-root (block 254,1) aka /dev/dm-1 (new data, after creating)
/dev/mapper/sunset-root--19--09 (block 254,3) aka /dev/dm-3 (old data, before creating)

all with same UUID, but it is only the first liltle problem. another problem is that fisrt device (dm-0) can`t be mounted, but udev
creates symlink in /dev/disk/by-uuid to it (on initramfs boot stage), so system can`t boot

other big problem for me is that update-grub rewrites my kopt=root=/dev/dm-1 rot UUID form

Revision history for this message
Ilya Petrov (ilya-muromec) wrote :

sorry, i misstyped affecting packages. i`m about grub/ubuntu (update-grub). please fix

Revision history for this message
Scott James Remnant (Canonical) (canonical-scott) wrote :

This is actually caused by the fact the kernel things dm-0 is mounted rather than the /dev/mapper/name; fix in progress

Changed in grub:
status: New → Invalid
Revision history for this message
Ilya Petrov (ilya-muromec) wrote :

no. /dev/mapper/sunset-root-real can`t be mounted.

initramfs need to mout /dev/mapper/sunset-root

Revision history for this message
Scott James Remnant (Canonical) (canonical-scott) wrote :

devmapper (2:1.02.20-1ubuntu4) gutsy; urgency=low

  * Make the device take the /dev/mapper name in all cases.
    LP: #126379, #144049.
  * Drop udeb patch since it's not needed.

 -- Scott James Remnant <email address hidden> Mon, 24 Sep 2007 13:37:29 +0100

Changed in devmapper:
status: New → Fix Released
Revision history for this message
Ilya Petrov (ilya-muromec) wrote :

still can`t boot after last upgrade.

I repeat : first device (dm-0 or /dev/mapper/sunset-root-real ) can`t be mounted!
it`s some internal lvm2 thing.

Revision history for this message
Ilya Petrov (ilya-muromec) wrote :

i think update-grub must not rewrite lvm (devmapper) names to UUID form because they are static and unique (in the case of snapshots UUIDs not)

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